Nonerosive, Immune-Mediated Polyarthritis in Dogs
Nonerosive immune-mediated polyarthritis is an immune-mediated inflammatory disease of the diarthroidal joints (movable joints: shoulder, knee, etc.), which occurs in multiple joints, and in which the cartilage of the joint (articular cartilage) is not eroded away. A type III hypersensitivity reaction, which causes antibodies to be bound to an antigen, in this case joint tissue, causes this condition.
These antibody-antigen complexes are called immune complexes, and they are deposited within the synovial membrane (where the fluid that lubricates the joints is held). There, the immune complexes trigger an abnormal immune response to the joint cartilage. What this means is that, in effect, the body is fighting against itself. This leads to an inflammatory response, and complement protein activation by the tissue surrounding the cartilage, in response to the immunity displaying cells, leading to the clinical signs of arthritis.
Symptoms
- Stiffness in legs
- Lameness
- Decreased range of motion
- Cracking of the joints
- Joint swelling and pain in one or more joints
- Joint instability, subluxation (partial dislocation) and luxation (complete dislocation)
- Often cyclic, comes and goes
Types
- Systemic lupus erythematosus: a noninfectious disease in which nuclear material from various cells becoming antigenic; autoantibodies (antinuclear antibodies) are formed to attack the body’s own joints
- Idiopathic polyarthritis: of unknown origin
- Polyarthritis associated with chronic disease: chronic infectious, neoplastic (uncontrolled growth of tissue), or enteropathic disease (intestinal disease)
- Polyarthritis-polymyositis syndrome: combination of arthritis in multiple joints, with weakness, pain, and swelling of the muscles
- Polymyositis syndrome: weakness, pain, and swelling of the muscles in the neck and legs
- Polyarthritis-meningitis syndrome: combination of arthritis in multiple joints with inflammation of the brain, with fever, pain, and stiff muscles
- Polyarthritis nodosa: arthritis in multiple joints with small nodular swellings
- Familial renal amyloidosis in Chinese shar-pei dogs: genetically predisposed condition causing deposits of hard, waxy protein fiber in the kidneys or surrounding area
- Juvenile-onset polyarthritis of Akita breed dog
- Lymphocytic-plasmacytic synovitis: swelling of the synovial membrane of the joint (where the lubrication for the joint is produced) as the result of antibody attack on the tissue
Causes
- Idiopathic (unknown)
- Immunologic mechanism likely: abnormal immune response to the system
- May occur secondary to a hypersensitivity reaction to sulfas, cephalosporins, lincomycin, erythromycin, and penicillins, involving the deposition of drug antibody complexes in the blood vessels of the synovium (lining of the joint)
- Chronic cases:
- Antigenic stimulation along with concurrent meningitis (brain swelling)
- Gastrointestinal disease
- Periodontitis: infection of the tissues that support the teeth
- Neoplasia: uncontrolled growth of tissue
- Urinary tract infection
- Bacterial endocarditis: bacterial infection of the heart lining
- Heartworm disease
- Pyometra: infection and accumulation of pus in the uterus
- Chronic otitis media (infection of the middle ear) or external fungal infections
- Chronic Actinomyces or Salmonella infections: bacterial infections, with fever, abscesses
Diagnosis
You will need to give your veterinarian a thorough history of your dog's health leading up to the onset of symptoms. Your veterinarian will perform a thorough physical exam on your dog, taking note of signs of pain, decreased range of motion, and any lameness. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, a urinalysis, and an electrolyte panel. In dogs suspected to have lupus erythematosus, a lupus erythematosus preparation or an antinuclear antibody test can be performed. Joint fluid aspirate will be taken for lab analysis, and submitted for bacterial culture and sensitivity. A biopsy (tissue sample) of synovial tissue will also help to make a definitive diagnosis.
X-ray images can also be used as a diagnostic tool. If a nonerosive, immune-mediated polyarthritis condition is present, it will be visible on the radiograph image.
pus
A product made of fluid, cell waste, and cells
polymyositis
A medical condition in which the smooth muscles become inflamed
otitis
A medical condition in which the ear becomes inflamed
radiograph
A record of body structures using an x-ray
synovitis
A medical condition in which the synovial membrane becomes inflamed
uterus
The hollow bodily organ that holds the embryo and fetus and provides nourishment; only found in female animals.
urinalysis
An in-depth examination of the properties of urine; used to determine the presence or absence of illness
meningitis
A medical condition in which the meninges becomes inflamed
subluxation
The displacement of the bone from its joint
luxation
The dislocation of a bone from the joint
aspirate
a) inhaling b) getting out fluid or gas by the act of sucking.
arthritis
A medical condition in which the joints become inflamed and causes a great deal of pain.
antigen
Any substance or item that the body of an animal would regard as strange or unwanted; a foreign disease or virus in the body (toxin, etc.)
biopsy
The process of removing tissue to examine it, usually for medical reasons.
endocarditis
An inflammation of the lining of the heart
lameness
Any type of pain or tenderness or lack of soundness in the feet or legs of animals
hypersensitivity
A reaction to a certain pathogen that is out of the ordinary
antibody
A protein in the body that is designed to fight disease; antibodies are brought on by the presence of certain antigens in the system.
